General water includes H2O (light water) together with D2O (heavy water) or DHO (semi-heavy water) which is a water molecule containing a deuterium atom as an isotope of a hydrogen atom. The concentration of heavy water and semi-heavy water contained in water existing in nature is approximately 150 ppm on a flat area, although depending on a sampling location, and most thereof is semi-heavy water.
The amount of heavy water and semi-heavy water contained in a human body is, for example, as small as 95 ppm of a body weight in a case of an adult having a body weight of 60 kg.
However, heavy water or semi-heavy water has physical properties such as a solubility for a substance, an electrical conductivity, and an ionization degree, and a reaction rate different from light water. Therefore, when a large amount of heavy water or semi-heavy water is taken, a disorder is caused in a living body, and a living thing dies in pure heavy water. Therefore, it is said that a lower deuterium concentration in drinking water or the like is more desirable for health of a human body, and verification has been developed.
Deuterium-depleted water containing little heavy water or semi-heavy water is not authorized by the Ministry of Health, Labour and Welfare in Japan, but is authorized as an anti-cancer agent for animals in Hungary, and is often taken by a cancer patient or the like.
As a method for producing deuterium-depleted water from general water, deuterium-depleted water has been conventionally produced by a method for repeating distillation utilizing a very small difference in physical properties between hydrogen and deuterium (Patent Literature 1) or a water electrolysis method (Patent Literature 2).
However, the conventional method for producing deuterium-depleted water requires large equipment and repeated complicated work, and has high production cost thereof. Therefore, a cancer patient or a person who wants to drink deuterium-depleted water expecting various effects has a large economic burden.